First, there seems to be a saturated market. You’ll have several people just like you and then the top registrars all to compete against. It’s not that you can’t beat the competition and get your share of the pie, it’s just that there may be easier outlets to get money.
Another drawback is the up front cost. For example, the pro plan is about $200 and basic is $90. That’s a decent chunk of change out of your wallet for something you will need to invest more time and money in.
Furthermore, you should not to buy a reseller package is to save money on your own registrations. If you’re a savvy enough domainer or webmaster, you can find promo codes lower than reseller prices.
I was also discouraged in that you really can’t SEO the store front unless you want to redesign it.
Last, if you plan on going the sponsored ads route, it doesn’t appear effective in an immediate ROI outlook. As you would expect, PPC prices are high and my conversion rate hasn’t been great. I’ve read the same from other resellers.
On the site, I give a price comparison chart on the cheapest domain reseller and how you can get a reseller pro plan for $65 less than Godaddy or WildWest but still get the same package. The savings should be a factor, but the real determination of whether to become a domain reseller is how determined you are to become your own registrar. To be successful, you have to utilize a great marketing campaign and make sure everyone knows they can buy domains from you.